As disclosed in U.S. Pat. No. 4,370,278 (Stahly et al.) and in copending applications Ser. Nos. 452,518 (Stahley et al. I), and 452,615 (Stahly), and 452,618 (Stahly et al. II), filed Dec. 23, 1982, and Ser. Nos. 487,038 (Lilje) and 487,039 (Lilje I), filed Apr. 21, 1983, it is known that nitroarylacetonitriles can be prepared by reacting a nitroaromatic compound with an alpha,alpha-disubstituted acetonitrile in an inert solvent and in the presence of a base--a reaction that appears to occur by a nucleophilic substitution mechanism and is therefore sometimes described in the references and herein as a nucleophilic substitution process.
It is also known that the nitroarylacetonitriles formed by the nucleophilic substitution process can be converted to the corresponding aminoarylacetonitiles by conventional methods of reduction, such as catalytic hydrogenation or the use of active iron powder; and Stahly et al. teach that the use of palladium-catalyzed hydrogenation is the preferred method of reduction.
Although satisfactory results have been obtained when a substantially pure nitroarylacetonitrile has been reduced by catalytic hydrogenation, as recommended by Stahly et al., erratic results, e.g., yields ranging from about 49-90%, have been encountered when that technique has been used for the reduction of the crude nitroarylacetonitriles prepared by nucleophilic substitution processes. It would obviously be desirable to find a reduction technique that could be used to provide consistently high yields of aminoarylacetonitriles from the crude nitroarylacetonitriles.